\begin{environ*}
    f(x) &= 10
       \\&= \command{
         something
         }
      g(x) &= \commandtwo{
        something else
      }
         \\&= g(x)
    \end{environ*}

    \begin{align}
      &x(
      asdasdlkj
      y)
      &= 1 \left(
        f(x)
      \right)
    \end{align}

    \[
      x &= 20
        &= 10
      \]

      \[
     x &= 10
       &= 20
     \]

      \begin{tabular}{cc}
        \begin{tabular}{c}
          Cell 1
      \end{tabular} &
      \begin{tabular}{c}
        Cell 2
      \end{tabular}
    \end{tabular}

    \begin{environ*}
      f(x) &= 10
           &= \begin{matrix}
             10 & 20 \\
         30 & 40
       \end{matrix}
       &= g(x) \\
  f(x) &= 5
       &= e - 1
\end{environ*}

\begin{environ*}
  f(x) &= 10
   &= \begin{matrix}
         10
       \end{matrix}
\end{environ*}
